As climate change tightens its grip on the world, institutions charged with protecting the most vulnerable nations could be faced with just such a question. Because there is no international consensus for ranking the possibilities of future devastation -- and because there are limited dollars lined up to help cope with climate change -- some countries already are battling over who will be considered most vulnerable.

"This is a major, major topic of discussion and debate at the moment," said Saleem Huq, head of the climate change group at the U.K.-based International Institute for Environment and Development.

Judging who is most threatened has real-world implications. Those at the top of the list -- if ever such a list is developed and agreed upon internationally -- could decide who is first in line to tap a multibillion-dollar Green Climate Fund.

The trail toward making such a determination, experts say, is strewn with scientific and political land mines. After all, many scientists consider China -- susceptible to droughts, typhoons and sea level rise -- to be the world's most threatened nation. But with a gross domestic product of $4.99 trillion, should it be as eligible for aid as poverty-stricken Bangladesh?

Some small island nations like the Seychelles are middle-income countries, yet climate change threatens their very existence. And where in the mix to put a Colombia or Pakistan, which doesn't fit neatly into any prescribed U.N. category yet suffers catastrophic flooding?

"There is simply no objective, scientific way of categorizing a ranking of 100-plus countries in order of who is more vulnerable than another," Huq said. "The moment someone comes up with a list, there's a problem."

Yet economists are trying. Last year, the British firm Maplecroft developed an extensive ranking that analyzed countries' exposures to weather extremes, sensitivity to damage tied to poverty, population, internal conflicts, dependence on agriculture, and capacity to adapt (Climatewire, Oct. 21, 2010).

And in January, former World Bank economist David Wheeler published a sweeping study quantifying the vulnerability of 233 nations, the risk to people in each of those countries from extreme weather events and agricultural loss, and putting the criteria in multiple dimensions.

'There's no one truth'
Wheeler, a senior fellow at the Center for Global Development, said the research is vital in order to sensibly allocate scarce climate change funding in proportion to the problems that countries are facing. He said it's important to consider not only the weather-related threats facing a country, but also the nation's ability to cope with crisis -- everything from per capita GDP to whether a country has strong governing institutions and control over corruption.

"We have to combine these different aspects. There's no one truth," he said. In Wheeler's assessment of nations rich and poor, China came out as far and away the world's most vulnerable nation overall, followed closely by India. Bangladesh and Trinidad and Tobago also made the top 10, as did the African nations of Central African Republic, Equatorial Guinea, Burundi, Sudan and Rwanda. But a different examination limited to just vulnerability to extreme weather risk found new countries on the endangered catalog, like Djibouti, Kenya, Somalia, Mozambique and the Philippines.

No rankings, experts agreed, take into account the political calculations that must also come into play when deciding how to prioritize and allocate money. Indeed, national leaders fiercely object to any ranking system that doesn't have their country at or near the top.

Phillip Muller, the Marshall Islands' ambassador to the United Nations, said comparing vulnerabilities is a near-impossible task. But one criterion he said should be paramount is a country's survivability.

"One definition I think we can start off with is to look at countries that would cease to exist if sea levels rise, or if there's a big hurricane or tsunami," said Muller, who fears that his own country of archipelagos will someday disappear beneath the waves.

And Farrukh Iqbal Khan, Pakistan's lead negotiator, who also chairs an adaptation fund board, said he believes countries need to consider the global impact of a catastrophe in a specific country. For example, he said, a struggle over water between Pakistan and India could reverberate worldwide -- but so would helping both nations to adapt.

"We must look at the global co-benefit, how to invest in areas that also contribute to addressing global impacts," Khan said.

Sparring over a dubious achievement
The issue came to a head at a U.N. climate change conference in Cancun, Mexico, last year when the G-77 group of developing nations sparred over who should be included in the definition of "vulnerable."

The 2009 Copenhagen Accord specifically cited least developed countries, small island developing states and Africa as "particularly vulnerable." That, negotiators said, caused unhappiness in Latin America, where leaders felt threats to their region were being ignored. But attempts in Cancun to categorize nations ended in a stalemate, and negotiators ultimately stayed vague, declining to elaborate on who should be included in the definition "particularly vulnerable."

Katherine Sierra, former vice president for sustainable development at the World Bank and now a senior fellow at the Brookings Institution, described the debate over vulnerability as "like a third rail" among developing nations.

But, Sierra said, there are models that new bodies like the Green Fund can look to for experience. The World Bank, for example, has an established formula for International Development Association (IDA) funds that go to the poorest countries that combines income level, institutional capacity, governance and other elements. By contrast, grants that the World Bank has doled out specifically for climate resilience were determined by an outside group of experts working with a set of specific criteria.

The Global Environment Facility, which implements an adaptation fund paid for by taxes on clean energy projects through the Kyoto Protocol, still has not finalized a way to prioritize funding, said Marcia Levaggi, manager of the adaptation fund secretariat. That discussion, she said, is still happening among the country representatives who make up the board.

'We are all in this together'
Heather McGray, a senior associate at the World Resources Institute which also is studying the issue, suggested a sequencing or rotation in which resources are directed to different regions in cycles.

As plans for the Green Fund go forward -- a transition board will meet in Bonn, Germany, in March -- Sierra said she expects discussions about broad categories of financial eligibility. But, she said, she doubts nations are ready to get specific about prioritizing money. "I think it's going to be very difficult politically to get this done," she said.

But for now, some point out, the fight over how to spend the money is almost a moot point. There is no money. The Green Climate Fund established in Cancun, which will manage most of a $100 billion annual pledge that nations have made, is not yet organized. And so far, the financial pledge is unfulfilled. Most countries have not even decided where the money will come from.

Wheeler in his study warned that the world doesn't have long to make choices. One aspect of the research that came through loud and clear, he said, was that climate change impacts are already being felt and there is little time to waste.

"All states may well be candidates for assistance in the uncertain, undoubtedly-turbulent world that awaits if we continue to dither on controlling carbon emissions," he wrote in the report. "We are all in this together, and my results indicate that dangerous climate change is already upon us."